from django.utils.safestring import mark_safe
"""
自定义的分页组件，以后如果想要使用这个分页组件，你需要做如下几件事
在视图函数中
    
    

def employee_list(request):

    data_dict = {} # 用于接收模糊查询的参数
    0. 如果有模糊查询
    q_name = request.GET.get('q_name')
    if q_name:
        data_dict['e_name__contains'] = q_name
    模糊查询条件结束
    
    # 1. 根据自己的情况去筛选自己的数据
    querySet = Employee.objects.filter(**data_dict)
   #2. 实例化分页对象
    page_object = Pagination(request,queryset)
    context = {
        "queryset": page_object.page_queryset,
        "page_string": page_object.html()
    }
    return render(request, 'employee_list.html', context)
    
    
在HTML页面中
 <ul class="pagination">
    {{ page_string }}
</ul>


"""

class  Pagination(object):
    def __init__(self, request,queryset,page_size=10,page_param='page',plus=5):
        """
        :param request: 请求的对象
        :param queryset: 符合条件的数据（根据这个数据给他进行分页处理）
        :param page_size: 每页显示多少条数据
        :param page_param: 在URL中传递的获取分页的参数 ,例如:/etty/list/?page=12
        :param plus:  显示当前页的前后几页(页码)
        """

        import copy
        query_dict = copy.deepcopy(request.GET)
        query_dict._mutable = True
        self.query_dict = query_dict

        self.page_param = page_param
        page = request.GET.get(page_param,"1")

        if page.isdecimal():
            page = int(page)
        else:
            page = 1

        self.page = page
        self.page_size = page_size

        self.start = (page - 1) * page_size
        self.end = page * page_size

        self.page_queryset = queryset[self.start:self.end]

        # 数据总条数
        total_count = queryset.count()

        # 总页码
        total_page_count, div = divmod(total_count, page_size)
        if div:
            total_page_count += 1
        self.total_page_count = total_page_count
        self.plus = plus


    def html(self):
        # 计算出，显示当前页的前5页，后5页
        if self.total_page_count <= 2 * self.plus + 1:
            # 数据库中数据比较少，没有达到11页
            start_page = 1
            end_page = self.total_page_count
        else:
            # 数据库中的数据比较多 > 11页
            if self.page <= self.plus:
                start_page = 1
                end_page = 2 * self.plus + 1
            else:
                # 当前页 > 5
                # 当前页+5 > 总页面
                if (self.page + self.plus) > self.total_page_count:
                    start_page = self.total_page_count - 2 * self.plus
                    end_page = self.total_page_count
                else:
                    start_page = self.page - self.plus
                    end_page = self.page + self.plus


        # 页码
        page_str_list = []


        # 首页
        self.query_dict.setlist(self.page_param,[1])
        page_str_list.append(
            '<li class="page-item"><a class="page-link" href="?{}">首页</a></li>'.format(self.query_dict.urlencode()))


        # 上一页
        if self.page > 1:
            self.query_dict.setlist(self.page_param,[self.page - 1])
            prev = '<li class="page-item"><a class="page-link" href="?{}">上一页</a></li>'.format(self.query_dict.urlencode())
        else:
            self.query_dict.setlist(self.page_param,[1])
            prev = '<li class="page-item disabled"><a class="page-link" href="?{}">上一页</a></li>'.format(self.query_dict.urlencode())


        page_str_list.append(prev)


        # 页码
        for i in range(start_page, end_page + 1):
            self.query_dict.setlist(self.page_param,[i])
            if i == self.page:
                ele = '<li class="page-item active"><a class="page-link" href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            else:
                ele = '<li class="page-item"><a class="page-link" href="?{}">{}</a></li>'.format(self.query_dict.urlencode(), i)
            page_str_list.append(ele)


        # 下一页
        if self.page < self.total_page_count:
            self.query_dict.setlist(self.page_param,[self.page + 1])
            next = '<li class="page-item"><a class="page-link" href="?{}">下一页</a></li>'.format(self.query_dict.urlencode())
        else:
            self.query_dict.setlist(self.page_param,[self.total_page_count])
            next = '<li class="page-item disabled"><a class="page-link" href="?{}">下一页</a></li>'.format(self.query_dict.urlencode())


        page_str_list.append(next)


        # 尾页
        self.query_dict.setlist(self.page_param,[self.total_page_count])
        page_str_list.append(
            '<li class="page-item"><a class="page-link" href="?{}">尾页</a></li>'.format(self.query_dict.urlencode()))


        # 搜索页
        search_string = """
               <li>
                   <form method="get" style="float:left;margint-left:-1px">
                       <input type="text" name="page" class="form-control" placeholder="页码"
                           style="position:relative;float:left;display:inline-block;width:80px;border-radius:0;">
                       <button style="border-radius:0" class="btn btn-default" type="submit">跳转</button>
                   </form>
              </li>
           """


        page_str_list.append(search_string)

        page_string = mark_safe("".join(page_str_list))
        return page_string
